Hi! I have two cats, Mochi and Dango. Mochi is 1 years old, and Dango is just about 10 weeks old. When Dango first came home two Saturdays ago, he immediately went to his base camp in a separate room. After a week, once both cats seemed ready, we introduced them. Introduction was a quick success! Mochi didn't growl or hiss at Dango at all, and soon after they played as well (although, I'm sure you can imagine what playing between a full grown cat and a kitten 1/4 of it's size would be like). To our pleasant surprise, by midday the first day, Mochi seemed really comfortable and was even willing to groom Dango as well during their midday nap.
Fast forward to 3 days after the initial meeting, Mochi is acting pretty strange. Day 1 and 2 seemed fine, but by Day 3 she didn't seem happy. She was as vocal as normal, and she wasn't very affectionate. By the end of Day 3, we noticed her cute crisp meows turned into very raspy and barely audible at times. We decided to put Dango back into his base camp for the night, and noticed on Day 4 (today) that she seemed a little more happy in the morning, however her raspiness still remained. Dango was rereleased and in a few hours, Mochi seemed pretty depressed again.
As I write this, I'm aware of the pattern and am pretty sure Dango is stressing her out in some way. I also read some cats can get depressed when there's a new kitten/cat in the household. Mochi has experience with foster kittens in the past, this didn't happen when they got old enough to be introduced and roam the house. I'm also very concerned about where the raspiness is coming from. I've been trying to play with Dango more so he doesn't bother her much, and for the most part she keeps her distance.
I would definitely appreciate some advice and whether this warrants calling the vet. Are these signs of depression and how can I help her out of it? Mochi has always been a really relaxed and outgoing cat. She likes watching outdoors from our numerous windows most of the day and has not engaged in a lot of interactive play anymore, despite us trying all types of wand toys. We love her very much and want her to be as happy and excited as we are. If necessary, we would be willing to start again with introductions as well, if that is the best course of action.